Obviously that's a tricky thing to do, like lots of things in poli sci. Not an exact science. Not really a science even imo
But you can ask these questions-
How many countries had a giant Civil War, the bloodiest in their history, over slavery? How many countries have states or provinces that still celebrate symbols of the side that lost?
How many countries have taken as much territory as we have in the past 300 years in as short a period as we have and had to reconcile with the fact we took someone's land as we continue to live here?
How many countries have dealt with as much racial tension/violence in the past 50 years as America?
Why is the U.S. #1 in the world in terms of prison population and incarceration rate?
Why did Donald Trump win an elecion on building a wall to keep an invading horde of Mexicans out?
Why did we separate children at the boarder from their families?